A thermal head has a plurality of resistance heating elements arranged on a substrate and first and second electrodes connected to the plurality of resistance heating elements. The thermal head prints, by heating the plurality of resistance heating elements, on a recording medium such as a heat-sensitive sheet in accordance with a signal. The plurality of resistance heating elements is heated by providing electric power to the plurality of resistance heating elements via the first and second electrodes.
One of the plurality of resistance heating elements is configured such that a connection end connecting with a first electrode has a smaller width than a connection end connecting with a second electrode, and another resistance heating element adjoining the one of the plurality of resistance heating elements is configured such that a connection end connecting with the first electrode has a larger width than a connection end connecting with the second electrode.
For each resistance heating element, the amount of heat generated on the first electrode side and the amount of heat generated on the second electrode side are different. Further, in this thermal head, an area of the first electrode in contact with the connection end and an area of the second electrode in contact with the connection end are different in accordance with the width of the connection end. Then, for example, when continuously applying current, for example, during actual printing, a larger amount of heat is accumulated in the electrode for the connection end having a smaller width, and accordingly, a position of transferred dot is displaced with respect to a position at an initial position toward the electrode for the connection end having the smaller width. Therefore, in this thermal head, the distance between a transferred dot made by one of the plurality of resistance heating elements and a transferred dot made by another resistance heating element adjacent to the one of the plurality of resistance heating elements in a direction in which the plurality of resistance heating elements are arranged. As a result, a quality of an image obtained by this thermal head is degraded due to a large amount of heat accumulated in proximity to each resistance heating element.